1. Technical Field
The present disclosure is directed to a signal processor for converting a digital input signal to a digital output signal and, more particularly, to a signal processor with an asynchronous sample rate converter.
2. Background
Mobile technologies and consumer electronic devices (CED) continue to expand in use and scope throughout the world. In parallel with continued proliferation, there has been rapid technical advance of device hardware and components, leading to increased computing power and incorporation of new peripherals onboard a device along with reductions in device size, power consumption, etc.
Such devices must routinely handle a range of signal types (e.g. audio signals, video signals, sensory data, etc.), often arising from a variety of sources. In order to manage arbitrary signals, it is common for such systems to implement sample rate converters to convert from a first signal with an arbitrary sample rate to an alternative sample rate. Such sample rate conversions may be used to lower computational signal processing requirements, synchronize signal sampling with a system clock, operate with a minimum sample rate, convert to a known sample rate, etc.
Furthermore, the input signals are typically provided from different sources having their own reference clock that differs in frequency, or operates asynchronously from available system clocks. Even though the variation in frequency may be small, due to stability requirements and performance demands in many applications, the data streams must still be sample rate converted in order to maintain synchronization and signal integrity over long sample streams. Use of an intermediate sample rate may also eliminate problems with switching synchronization of signal sources. For example, when a signal processing system is synchronized to an input sample stream (rather than an independent or stabilized clock) and the sample stream clock changes, fluctuates, or is removed, “glitches” in generated output signals can occur.
Such problems as described above are of particular relevance to the areas of audio processing, video processing and telemetry applications.